This chapter introduces Essays in Applied Musicology. It rehearses the zygonic conjecture, which holds that the essence of music is one sound or group of sounds being heard to derive from another through the imitation of one of its features or more. It is this sense of derivation through imitation that enables listeners to hear a series of discrete sonic events as a coherent stream of abstract sounds – as ‘music’. The four chapters that make up Essays in Applied Musicology comprise a new study on the emergence of musical abilities in the early years, using the Sounds of Intent framework of musical development; an exploration of how the Sounds of Intent model can be extended to map how people with learning difficulties engage in creative multisensory activities; an investigation of the expectations generated on hearing a piece of music more than once evolve in cognition, using evidence from a musical savant; and a report on the effect on listeners of repeated exposure to a novel melody. The chapter concludes by noting that a single underlying principle – a sense of derivation through imitation – is sufficient to offer concise and elegant explanations of diverse cognitive phenomena pertaining to music.